Carnation Creek Watershed Experiment

The effects of forestry practices on watershed processes and salmon populations have been studied at the Carnation Creek Experimental Watershed on the southwest coast of Vancouver Island, British Columbia since 1970.

Carnation Creek fish-forestry interaction research was initiated by Fisheries & Oceans Canada and MacMillan Bloedel Ltd. together with federal and provincial government partners including the Canadian Forest Service and the B.C. Forest Service. Today, the B.C. Ministry of Environment and Climate Change Strategy continues and leads this research into long-term, forestry-related effects and watershed recovery processes in collaboration with key government and industry partners.

This intensive, single-watershed case study has generated the longest series of continuous data on fish-forestry interactions in the world. The comprehensive, multi-disciplinary study has made major contributions to B.C. forestry legislation, regulations, and guidelines in the 1980s and 1990s. It continues to inform best management practices today.

In order to understand forestry related impacts and recovery processes over different time scales, there is a continuing need for watershed-scale, process-oriented studies that:

Provide information on the effects of forestry practices

Are conducted over sufficient periods of time

Incorporate pre-harvest and post-harvest research phases

The Carnation Creek Experimental Watershed is one site where these relationships can be thoroughly studied and understood. This study is responsible for much of our present understanding of how small Pacific coastal watersheds function, and how forestry practices affect these functions.

Location Map

The interactive map below details several points of interest relating to the Carnation Creek Watershed Experiment. Carnation Creek is located, about 20 kilometres northeast of Bamfield on the south shore of Barkley Sound in southwestern Vancouver Island (49°N, 125°W).

For each point of interest, click on the red button to view pictures and more information (PDF):

In the 1960s, studies of the effects of logging on fish populations had been conducted in Oregon, Alaska and New Hampshire, but B.C. did not have any local studies upon which to base management decisions. The Carnation Creek study was initiated in order to provide information on the effects of forest practices on water, streams and fish habitats and populations (fish-forestry interaction) on at least one type of drainage basin in coastal B.C.

At the beginning of the study, during the early years of fish-forestry interaction research, the three principal objectives were to:

Provide an understanding of the physical and biological processes operating within a coastal watershed

Reveal how the forest harvesting practices employed in the 1970s and early 1980s changed these processes

Apply the results of the study to decision-making concerning land-use management and aquatic habitat protection

Currently, the overall project objective is to determine the mechanisms, rates and levels of impact and recovery relative to historic forest practices by quantifying long-term changes in biological and physical processes at the watershed scale as the second forest grows.

Key Project Questions

1. What is the long-term effect of high levels of historic watershed harvesting (65 percent) on:

Hillslopes (mass wasting)

Riparian (streamside forest) function

Channel morphology and fish habitats

Salmon populations

2. How long do these physical and biological changes persist?
3. Are all forestry-related impacts immediate or are their delayed ones?
4. Can watersheds and streams recover on their own?
5. Are there implications for watershed/stream restoration?
6. What has been the contribution of climate variability to observed changes?
7. What are the implications for second-pass forestry practices in coastal watersheds with impacts remaining from the first pass?

To answer our key questions, a multi-disciplinary, integrated research and monitoring approach is necessary. Key project components continue to include studies of salmon populations including coho and chum salmon and sea-going rainbow (steelhead) and cutthroat trout.

The Carnation Creek project is a single-watershed, intensive case study incorporating pre-harvest, during-harvest, and post-harvest observations. Spatial controls are available for a variety of study components in Tributary C, a sub-basin mainly unharvested for the duration of the investigation. This study was designed initially to examine the effects of progressive clearcutting and three different types of streamside (riparian) forest harvest treatments on stream channels and fish populations. The three riparian treatments applied within the lowermost 3.1 km of the stream were:

a leave-strip buffer 1–70 m wide from the estuary to 1300 metres upstream;

“intensive” clearcutting along 900 metres of stream channel immediately upstream from the leave-strip treatment (no riparian trees were left, some trees were felled and yarded across the stream, and commercially valuable windthrown trees were recovered from the stream channel); and

“careful” clearcutting along 900 metres of stream immediately upstream from the intensive treatment area (no activity was permitted in the stream; vegetation on the streambank, such as salmonberry, was untouched but red alders were removed).

The study was carried out in three phases:

pre-harvest period, 1970–1975;

during-harvest period, 1976–1981, when about 41% of the watershed (including almost all of the valley bottom) was harvested; and

post-harvest period, currently from 1982 to the present. Within the post-harvest phase (1987–1995), about 21 percent more of the basin was logged in headwater areas.

Forest harvesting changes the hydrological cycle beginning with forest canopy precipitation (e.g., rainfall) interception and the amount and speed of runoff to stream channels). The time to return to pre-harvest conditions,” hydrologic recovery”, is determined through sub-canopy microclimatology and rainfall interception and runoff.

Rain gauges and sampling troughs in both mature forest and second-growth stands are used to determine the proportion of rainfall that is intercepted by the vegetation and channelled down tree trunks (stem-flow monitoring) to the ground.

Hydrologic recovery models are developed and continually validated on the basis of these field data.

Annual ground-based surveys have been conducted in eight representative study sections (60–120 metres long) distributed in both clearcut and riparian-buffered stream areas. Cross-sectional and longitudinal profiles are obtained to describe the geomorphic characteristics of each study section.

All pieces of large woody debris (LWD) are mapped and identified with numbered, metal tags to follow changes in distribution and abundance. Textural distributions of surface sediments are described visually with grid samplers and mapped.

Annual channel scour and deposition is quantified with scour-and-fill monitors installed within the channel.

Sediment (bedload) transport is determined by following the distribution of large populations of magnetically tagged, colour-coded stones representing natural size distributions and placed into the stream in previous years. Particles are located with magnetometers and laser survey equipment to calculate distances and depths moved over time.

Using data from these surveys, triangulated irregular networks (TIN) were created. The TINs were converted to five centimetres digital elevation models (DEM) and subtracted from the earliest surface to assess channel fill and scour in the research locations.

At study area III, the channel has migrated considerably, especially in recent years. This has caused a two-to-three metre high bank to be eroded, yet the site appears to be aggrading (infilling with excess sediment) .

At study area V a logjam formed in the middle of the channel in the early 1980s, forcing the channel to aggrade. In response, multiple channels formed and downcutting into the tributary occurred, resulting in the modern channel.

Study area VIII, like study area V, experienced a large channel spanning log jam in the 1980s which caused upstream aggradation. Unlike study areas IV or V, the channel managed to migrate around the wood and subsequently removed the deposited material.

Adult coho and chum salmon, and cutthroat and steelhead trout spawners returning to Carnation Creek (September to mid-December) are enumerated at the main fish weir located near the mouth of the stream.

Each spawner is identified to species and sex. Age is determined from scale samples. Lengths and weights are obtained.

Chum salmon spawning downstream of the main fence are enumerated each day by observers on foot. Their seasonal abundance is determined from "area-under-the-curve" techniques.

Juvenile salmon (fry and smolts) and sculpins migrating seaward in spring (mid-February to mid-June) are enumerated and identified to species, and large numbers (up to 50 individuals per species per day) are sampled for scales, measured for length, and weighed.

Coded-wire tags are applied to all coho salmon smolts to determine marine survival.

Multiple fish surveys are performed each summer to describe the abundance, distribution, age structure, growth, and survival of juvenile salmonids rearing in the watershed. Changes in these numbers over the years is a strong reflection of changes in the capacity of the stream to produce salmon.

Three surveys are conducted in 10 representative study sections (60–120 metres long) distributed in clearcut and riparian-buffered stream areas between mid-June and late September. Eight of these study sites are the same as, or adjacent to, those used for channel morphology research.

Abundance of each species by study site is determined by two-catch removal method with electrofishing, seining, and barrier nets. Lengths, weights, and scales for age analysis are taken.

The total abundance of fish in Carnation Creek is determined by extending the numbers captured in the survey sections to the total length of stream inhabited by each species.

Aquatic habitat inventories for fish rearing in Carnation Creek are obtained simultaneously with the fish inventories. Habitats are described for periods of summer base flows within each study section–Resource Information Standards Committee (RISC) standard methods are used to quantify channel, pool, glide, and riffle habitat units for fish density determinations.

Seasonal and interannual changes in numbers and fish size are determined to track fish species survival and growth by riparian treatment area, by channel impact state, and in the watershed overall.

Juvenile salmonid movement between the main channel and tributary ̶ or off-channel ̶ overwintering refugia are quantified by two-way fish fences operated in autumn and spring.

Baited fish traps and snorkel counts are also used to assess the proportion of juvenile populations overwintering in the main channel versus tributary/off-channel habitats.

Post-harvest habitat assessment, and use of these sites by rearing fish, are determined annually to assess the importance of low-order streams for salmon survival and production.

Total overwinter survival is calculated from the difference between the population abundance determined in late summer / autumn and the number of smolts migrating seaward from Carnation Creek in spring (plus residual fish rearing in the stream in spring).

C-weir

Mayfly

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